Evolution axiale du coefficient de transfert de matière en colonne à bulles et en lit fluidisé triphasique

Liquid phase volumetric mass transfer coefficients for oxygen are determined in a three-phase fluidized bed and in a bubble column. The concept of exponential decreasing axial variation of volumetric mass transfer coefficient leads to a better representation of oxygen concentration profiles inside the column. Compared to the bubble column, k_la axial variations are more important in the lower part of the fluidized bed column, where solid particles increase the coalescence phenomenum, particularly with viscous liquids.     

Measurement of residual stresses in injection‐molded polymer parts by time‐resolved fluorescence

Time‐resolved fluorescence properties of 9‐methylanthracene (9MAn) dispersed in film of polyvinylchloride (PVC) containing carbon black were studied under tensile loadings. The fluorescence lifetime of 9MAn decreased from 5.70 to 5.55 ns, whereas the stresses acting on the films increased from 0 to 3 MPa. The change in fluorescence lifetimes of 9MAn during the stress relaxation process showed that the fluorescence lifetimes were correlated with the stresses, not with the strains. The results suggest that 9MAn is a useful probe for monitoring stresses acting on the matrix. With the use of the fluorescence properties of 9MAn, the residual tensile stresses on the skin‐layer of PVC injection‐molded test pieces were estimated. The estimated residual stresses were about ～ 1 MPa. The residual stresses were relaxed to 0 MPa with annealing at 100°C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2600–2603, 2002     

基于ARM9的自适应模糊PID定长切割控制系统

针对管材在线定长切割过程中位置和速度跟踪控制的难点问题,研发了以基于ARM9 S3C2416微处理器的控制器为核心的定长切割控制系统,并且采用基于自适应模糊PID控制器的伺服闭环控制系统,实现了管材定长切割的高精度控制。主要讨论了定长切割控制系统的硬件和软件设计、伺服系统建模、自适应模糊PID伺服跟踪技术的应用。实践证明:该控制系统采用触摸屏代替PLC,功能稳定,实时性高,操作灵活方便;采用自适应模糊PID控制器可明显提高其动态响应性能及定长切割的精度,使控制系统具有成本低、可靠性高、抗干扰能力强、控制精度高等优点,能够满足定长切割的精度要求。     

用于测定钢液低氧含量的双层固体电解质研究

采用“毛坯浆料法”在ＺｒＯ２（９％摩尔含量ＭｇＯ）管状固体电解质基体表面制备了厚度为１－４μｍ的ＺｒＯ２（１０％摩尔含量Ｙ２Ｏ３）固体电解质涂层，并分别对此在本实验室和美国ＬｅｅｄｓａｎｄＮｏｒｔｈｒｕｐ公司进行了钢液低氧含量测试，结果表明：涂层没有破坏基体的抗热震性：氧浓差电池电动势的重现性偏差由原来的±２ｍＶ；电动势的绝对值提高１０ｍＶ左右；而比日本Ｔｏｒａｙ公司的同类产品提高３５ｍＶ，这说明     

9-蒽甲酸/卟啉钯衍生物的pH响应上转换性能

以9-蒽甲酸(9-ACA)为发光剂,八乙基卟啉钯(Pd OEP)为光敏剂,在二者最佳配比〔n(9-ACA)∶n(Pd OEP)=80∶1〕下,构建了对溶液中氢离子和氢氧根离子具备灵敏响应性的上转换发光体系9-ACA/PdOEP。当pH处于4～8以及8～11时,上转换发光强度均与pH呈现良好的线性关系。参比实验中,单一组分9-ACA本身的荧光强度与pH没有呈现线性关系,证明了9-ACA/Pd OEP体系对于pH的宽范围响应来源于光敏剂与发光剂之间的三线态-三线态能量转移(TTET)过程。     

嵌入式Linux系统下CC1101的驱动与应用

CC1101在工业及实验室均有着广泛的应用,本文完成了基于ARM9硬件平台和嵌入式Linux系统的CC1101驱动开发,并以此为基础提出一种简单面向连接的通信模型。经验证,这种通信模型能够保证CC1101的通信质量。     

Electrical conductivity and redox stability of La2Mo2−xWxO9 materials

A series of compounds La₂Mo_2−xW_xO₉ (x = 0-2) were synthesized using a freeze-dried precursor method at relatively low temperatures (673-823 K). These materials were characterised by thermogravimetric and differential thermal analysis (TG/DTA), differential scanning calorimetric (DSC), X-ray diffraction (XRD), and transmission electron microscopy (TEM) and dilatometric measurements. Oxygen stoichiometry was evaluated by coulometric titration and thermogravimetric analysis at 873-1273 K. The ionic and electronic conductivities of these materials were analysed by impedance spectroscopy and a Hebb-Wagner ion-blocking method under moderately reducing conditions. The presence of W⁶⁺ leads to an increase of the stability range (about 10⁻¹⁶ Pa for La₂Mo_0.5W_1.5O₉ at 1073 K) and prevents oxygen loss and amorphisation. Within the stability range, the electronic conductivity increases gradually as the temperature increases and as the oxygen partial pressure reduces. This indicates that the electronic transport is mainly n-type as a result of the oxygen-content decreasing in the molybdate lattice. Further reduction of the oxygen partial pressure gave rise to the decomposition of La₂Mo_2−xW_xO₉, leading to the formation of new phases with molybdenum in lower oxidation states, which further enhances the electronic conductivity. The results of the coulometric titration and the thermogravimetric studies under a dry 5% H₂/Ar flow suggest that tungsten doped lanthanum molybdate materials can be used as electrolyte only at low temperature and under moderate reducing conditions.     

Trail-following responses of the Argentine ant,Iridomyrmex humilis (Mayr), to a synthetic trail pheromone component and analogs

Behavioral evidence indicates that (Z)-9-hexadecenal (Z9-16ALD) is a trail pheromone component ofIridomyrmex humilis, and that the true trail pheromone may be multicomponent. Trail-following responses ofI. humilis workers to several concentrations of syntheticZ9-16ALD, a constituent of the Pavan's gland, were found to be comparable to responses to gaster extract trails containing ca. 100 times lessZ9-16ALD. Of the five aldehyde analogs tested, only (Z)-7-hexadecenal (Z7-16ALD) elicited significant trail-following. However, following responses to severalZ9-16ALD-Z7-16ALD combinations were lower than responses toZ9-16ALD alone. Trails on filter paper of biologically relevant concentrations ofZ9-16ALD lose activity within 2 hr in the laboratory. The release rate ofZ9-16ALD measured from filter paper trails was 0.25 ± 0.10 pg/cm-sec. This was used to estimate the trail-following threshold for this compound of Argentine ant workers.     

Decolorization of organic dyes on Pilkington Activ™ photocatalytic glass

The air–solid photocatalytic degradation of organic dye films Acid Blue 9 (AB9) and Reactive Black 5 (RBk5) is studied on Pilkington Activ™ glass. The Activ™ glass comprises of a colorless TiO₂ layer deposited on clear glass. The Activ™ glass is characterized using atomic force microscopy (AFM) and X-ray diffraction (XRD). Using AFM, the TiO₂ average agglomerate particle size is 95 nm, with an apparent TiO₂ thickness of 12 nm. The XRD results indicate the anatase phase of TiO₂, with a calculated crystallite size of 18 nm.

Dyes AB9 and RBk5 are deposited in a liquid film and dried on the Activ™ glass to test for photodecolorization in air, using eight UVA blacklight-blue fluorescent lamps with an average UVA irradiance of 1.4 mW/cm². A novel horizontal coat method is used for dye deposition, minimizing the amount of solution used while forming a fairly uniform dye layer. About 35–75 monolayers of dye are placed on the Activ™ glass, with a covered area of 7–10 cm². Dye degradation is observed visually and via UV–vis spectroscopy.

The kinetics of photodecolorization satisfactorily fit a two-step series reaction model, indicating that the dye degrades to a single colored intermediate compound before reaching its final colorless product(s). Each reaction step follows a simple irreversible first-order reaction rate form. The average k₁ is 0.017 and 0.021 min⁻¹ for AB9 and RBk5, respectively, and the corresponding average k₂ is 2.0 × 10⁻³ and 1.5 × 10⁻³ min⁻¹. Variable light intensity experiments reveal a p = 0.44 ± 0.02 exponent dependency of initial decolorization rate on the UV irradiance. Solar experiments are conducted outdoors with an average temperature, water vapor density, and UVA irradiance of 30.8 °C, 6.4 g water/m³ dry air, and 1.5 mW/cm², respectively. For AB9, the average solar k₁ is 0.041 min⁻¹ and k₂ is 5.7 × 10⁻³ min⁻¹.     

Modèles Hydrodynamiques pour la Séparation des Courants dans un Décanteur Pilote

Despite of its general use in industry, particle sedimentation is still a not well understood unit operation. Hydrodynamics is complex in essence, mainly because the possible volumes are depending on the operating conditions, which in turn has consequences on the stability of the equipment in unsteady state conditions.